1. Field of the Invention
The present invention relates to a joint which, by realizing two metal seals with interference engagement activated by a screwable sleeve, makes it possible an easy, effective and cheap rapid, tight-seal connection of two pipes with each other to be accomplished with no need for said two pipes to be submitted to a revolutionary movement.
2. Discussion of Background
As known, in petroleum field and in particular in the operations for well completion, the need exists for connecting the production tubing with the so said tubing hanger at the wellhead. In the case of a single completion, said connection is made by simply screwing the single tubing onto the tubing hanger, a solution which is anyway impossible in the case of multiple completions, i.e., in the presence of two or more tubings to be connected, but using the expensive and complex through-adapter tubing hangers.
In order to obviate the above drawback, joints have been developed which make it possible the tubings to be connected with said tubing hanger, with no need for said tubings to be submitted to a revolutionary movement.
The joints known from the prior art substantially comprise a female hollow body to be butt-fastened to a tubing section, a male hollow body cooperating with said female body and to be fastened onto said tubing hanger, a first sleeve suitable for being screwed onto said male body in order to cause the elastomeric-elements seal provided between said bodies to become operating, as well as a second sleeve suitable for being screwed down onto said female body in order to ensure the mechanical continuity.
Unfortunately, such a kind of joint, besides a certain mechanical complexity, requires the use of two sleeves; and it does not ensure, with its elastomeric elements, an effective tightness of the sealing over time, in particular under such hostile operating conditions as generally met in petroleum field.
In order to accomplish a better seal tightness, in certain joints known from the prior art, a gasket was adopted which is constituted by a low-yield metal ring, but also this solution does not offer a high enough reliability, as required in the concerned field.